For any sufficiently large codebase, the agent only ever has a very % of the code loaded into context. Context engineering strategies like "skills" allow the agent to more efficiently discover the key information required to produce consistent code.
mostly because reading the code base fills up the context window; as you aggregate context, you then need to synthesize the basics; these things arnt intelligence; they dont know whats useless and whats useful. They're as accurate as the structureyou surround them with.